Photographic fixing-bath.



UNITED STATES PATENT OFFICE.

ARTHUR EIOHENGRUN, OF ELBERFELD, GERMANY, ASSIGNOR TO FARBEN- FABRIKEN OF ELBERFELD 00., OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

PHOTOGRAPHIC FIXING-BATH.

SPECIFICATION forming part of Letters Patent No. 710,568, dated October '7, 1902. Application filed May 28,1902. Serial No. 108.703. (No specimens.)

To a whom it may concern:

Be it known that I, ARTHUR EIonENcEiiN, doctor of philosophy, chemist, residing at Elberfeld, Germany, (assignor to the FARBEN- FABRIKEN OF ELBERFELD Co. of New York,) have invented a certain new and useful Improvement in Photographic Fixing-Baths, of which the following is a specification.

As is known, neutral acid sulfites and thio- IQ sulfates of alkalies are employed in photography as admixtures to photographic fixing-baths. The use of these sulfites is, how ever, accompanied by many disadvantages. For instance, the solutions cannot be pre- 1 served for any length of time without becoming cloudy, and the sulfites are decomposed by the action of the air, precipitates being thus formed which spoil the photographic pictures immersed in them. I have now found that these disadvantages can be obviated by employing instead of the above-mentioned sulfites the addition compounds obtained from ketones and bisulfites, especially the compounds which are prepared from acetone 2 and the potassium or sodium bisulfites, the so-called acetone alkali bisulfites having the following general formula:

CH OH C 3 011 so,M,

M meaning an alkali metal, such as potassium or sodium. These addition compounds have the great advantage that they are readily soluble in water and that even their concentrated solutions keep long in a well-corked bottle without decomposing.

The following formula can be employed with good effect as a fixing-bath: one hundred parts of sodium thiosulfate, four parts of potassium acetone bisulfite, and four hundred parts of water.

The fixing agent produced as above will keep for an extraordinarily long time and can be used over and over again, as it remains clear, as well as colorless, for a very long time. 5

Having thus described my invention and in what manner the same is to be performed, what I claim as new, and desire to secure by Letters Patent, is-

The herein-described new fixing agent containing aceton e alkali bisulfite and alkali thiosulfate, substantially as hereinbefore described.

In testimony whereof I have signed my name in the presence of two subscribing witnesses.

ARTHUR EIOHENGRUN.

'Witnesses:

Orro Konrc, T. A. RITTERHAUS. 

